Zeolite-ruthenium-borane catalyst composition

ABSTRACT

A composition useful in catalytic reactions comprising ruthenium metal on a faujasite-type of zeolite which is subsequently treated with a borane solution and calcined under special conditions is disclosed herein.

FIELD OF THE INVENTION

This invention relates to a catalyst composition comprising rutheniummetal on a zeolite support which is subsequently treated with borane.Such compositions are useful in syngas catalysis, hydrogenationreactions and dimerization processes.

BACKGROUND OF THE INVENTION

Supported ruthenium catalysis have been utilized in syngas reactions,hydrogenation reactions, and oligimerization reactions. The instantcompositions comprising zeolite supported ruthenium treated with boraneexhibit catalytic priorities significantly different from traditionallysupported ruthenium compounds.

SUMMARY OF THE INVENTION

The instant invention comprises catalyst compositions prepared by ionexchanging ruthenium containing solutions with faujasite type zeolites,calcining and then reducing the ruthenium containing zeolite,subsequently contacting the ruthenium containing zeolite with borane,and subsequently calcining in air and then reducing the borane treatedmaterial. Compositions prepared in this fashion have catalyticproperties that differ from traditionally supported ruthenium materialssuch as for example ruthenium supported on zeolite alone, or rutheniumon a silica-alumina. They also differ significantly from similarcompositions described in applicants' copending application Ser. No.410,298, filed Aug. 23, 1982 wherein the composition is calcined innitrogen rather than air just prior to the final reduction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The instant invention comprises a catalyst composition prepared by:

a. ion-exchanging the sodium ions of the sodium form of a faujasite typezeolite with ruthenium ions by contacting said zeolite with a solutioncontaining a soluble ruthenium compound,

b. calcining the ruthenium exchanged zeolite in nitrogen at atemperature ranging from about 300° C. to about 600° C.

c. contacting the ruthenium-containing zeolite with hydrogen at atemperature ranging from about 300° C. to about 600° C. whereby theruthenium is reduced to the metal,

d. contacting the ruthenium metal-containing zeolite with a solution ofborane,

e. calcining the borane-treated zeolite in air at a temperature rangingfrom about 300° C. to about 600° C. and then

f. contacting the borane-treated zeolite with hydrogen at a temperatureranging from about 300+ C. to about 600° C.

The zeolite used in the instant invention is of the faujasite type andis utilized initially in the sodium form, that is, the various exchangesites are satisfied by sodium. Such zeolites are described in U.S. Pat.Nos. 2,882,244, usually referred to as X zeolite and 3,216,789 referredto as a Y zeolite, and also in 3,446,727. These faujasitic type zeoliteshave been widely employed in catalytic processes such as for theconversion of hydrocarbons and are generally well known. The patent andgeneral literature is extensive on these. In preparing the instantcompositions, the sodium form of the faujasite type zeolite is contactedwith a solution of a ruthenium salt whereby the ruthenium ion ision-exchanged with the sodium ion. Any suitable, soluble ruthenium saltcan be utilized, dissolved in an appropriate solvent. Suitable salts andsolvents are readily determined by one skilled in the art. Illustrativeexamples of suitable ruthenium salts include salts such as ruthenium(III) chloride hydrate, ruthenium (III) bromide, anhydrous ruthenium(III) chloride and ruthenium nitrate. Also suitable are the ammoniacomplexes of the ruthenium halide such as for example Ru(NH₃)₆ Cl₃ andRu(NH₃)₆ I₃. Salts of suitable organic acids are also suitable. Here,examples include ruthenium (III) acetate, ruthenium (III) propionate,ruthenium hexafluoracetylacetonate, ruthenium (III) triofluoracetate,ruthenium octanoate, ruthenium naphthenate, ruthenium valerate, andruthenium (III) acetylacetoneate.

Suitable solvents for the desired ruthenium compounds can readily bedetermined by simple experimentation. Preferred solvents are water andthe lower alkanols. After contacting the sodium form of the zeolite withthe ruthenium-containing solution, the ruthenium-exchanged zeolite isdried and then calcined in nitrogen at a temperature ranging from about300° C. to about 600° C. After calcination, the ruthenium-containingzeolite is reduced in a hydrogen atmosphere at a temperature rangingfrom about 300° C. to about 600° C. The reaction time is not criticalbut is adjusted according to the temperature of reduction, higherreduction temperatures will require shorter times and vice versa. Thereduction conditions are chosen such as to reduce the ruthenium which isan ionic form in the zeolite to ruthenium metal which will be depositedon the surfaces (external and pore volume) of the zeolite.

The ruthenium metal containing zeolite is then contacted with a solutionof borane (BH₃ or diborane B₂ H₆) in a suitable organic solvent.Suitable solvents comprise the ether solvents, particularly suitable istetrahydrofuran. The borane is typically prepared by the reaction of ametal hydride with a boron halide in an ether-type solvent. The boranecompounds are sensitive to both air and moisture so the above mentionedimpregnation of the zeolite with the borane compound must be maintainedunder anhydrous, air-free conditions.

After the zeolite has been impregnated with the borane solution, it isdried at relatively low temperatures up to about 50° C., and thencalcined on air at a temperature ranging from about 300° C. to about600° C. The calcined borane-treated zeolite is then reduced in ahydrogen atmosphere at a temperature ranging from about 300° C. to about600° C. Calcination and reduction times are not critical and range fromabout 0.1 to about 20 hours.

The resultant catalytic material is used in a fashion typical of thatutilized for heterogenous catalysts. It may be used in fixed beds, influidized beds or in batch reactors. The preparation of the catalyticcompositions and their use in typical processes will be furtherdescribed below by the following illustrative embodiments which areprovided for illustration and are not to be construed as limiting theinvention.

ILLUSTRATIVE EMBODIMENTS Composition Preparation

The following example illustrates the typical preparation of acomposition falling within the scope of the instant invention. 30 Gramsof Ru(NH₃)₆ Cl₃ are dissolved in 150 cc of water and added to a 50 cccondensing flask. 60 Milliliters of the sodium form of Y zeolite(L24-52/RW Linde) was calcined for 24 hours at 500° C. and then added tothe reflux flask and refluxed for about two hours. The zeolite was thenfiltered and washed with approximately 500 cc of water. The zeolite wasthen placed in a quartz flow tube and calcined in a nitrogen flow (atabout 550° C. for about five hours). The temperature was raised fromroom temperature to 550° C. at a rate of approximately 10° C. perminute. After calcining, the quartz flow tube was cooled and thehydrogen flow was initiated through the tube. The temperature was thenagain raised to about 500° C. at a rate of about 10° C. per minute. Thematerial was maintained at 500° C. for about two hours. After reductionthe sample was cooled to room temperature. Twenty-five cubic centimetersof the ruthenium-treated zeolite was contacted with 125 cc of a onemolar solution of BH₃ in tetrahydrofuran. The borane-treated materialwas then dried at about 40° C. on a rotovac dryer for about three hours.The sample was then placed in a quartz tube, air flow was initiated andthe tube was heated at about 10° C. per minute to about 550° C. forabout five hours. After calcination the sample was cooled, hydrogen flowwas then initiated over the sample, and the sample was heated to about500° C. at a rate of about 10° C. per minute for about two hours. Afterthis reduction, the sample was cooled overnight. During the abovepreparative techniques, the sample was maintained under dry boxconditions except for the calcination and reduction process.

Process

The composition, according to this invention, (Example 1) was preparedin the fashion described above. Analysis of this composition showed thatit had approximately 6 wt % ruthenium and about 0.97 wt % boron. Thesample was placed in a tubular flow reactor and heated to theappropriate reaction temperature as indicated in Table 1. Carbonmonoxide and hydrogen in a molar ratio of about 1:1 were fed to thereactor under the conditions indicated in Table 1. The products of thereactor were analyzed by gas chromotography and C¹³ nuclear magneticresonance and the results are shown in Table 1 below. Greater than about70 wt % of the products were paraffins within the C²⁵ -C³⁵ range withthe average carbon number around 30. For comparative purposes, othercompositions not falling within the scope of this invention wereprepared. Example A comprises a composition prepared according to theteachings of applicants' copending application Ser. No. 410,298, filedAug. 23, 1982 wherein just prior to the final reduction the compositionis calcined in nitrogen rather than air. Example B comprises a rutheniummetal supported on a Y zeolite. This is basically the same as Example 1without the borane treatment. Example C comprises the use of analumina-silica as a support rather than a zeolite. The alumina-silica isDavison 980-25 which has a similar Al/Si ratio as the Y zeolite. Thisexample was prepared in the same fashion as Example 1 except without theborane treatment. As can be seen from the table, the composition of theinstant invention provides as high selectivity to paraffins with carbonnumbers around thirty as compared to the other examples which providelower paraffins, olefins and oxygenates.

Catalysts prepared according to the instant invention will alsodemonstrate activity for the dimerization of olefins to higheroligomers.

                                      TABLE 1                                     __________________________________________________________________________    Syngas Conversions by Ru/B/Y and Related Catalyst                             Example       1     A    B    C                                               Catalyst:     Ru/B/Y                                                                              Ru/B/Y                                                                             Ru/Y Ru/A1-Si*                                       __________________________________________________________________________    Ru %          7.1   6.00 7.10 3.96                                            B %           1.02  0.97 --   --                                              GHSV          4300  4000 4000 4000                                            Temperature (°C.)                                                                    250   250  220  250                                             Pressure (PSIG)                                                                             1000-1500                                                                           1500 1800 1500                                            % Syngas (1:1) Conversion                                                                   15.5  6.4  5.1  2.8                                             Molar Selectivity %                                                           Overall                                                                            In C.sub.5.sup.+                                                         C.sub.1                                                                            Methane  3.2   20.6 12.8 22.6                                                 Methanol 0.4   3.8  0.6  0.78                                            C.sub.2                                                                            Ethylene/Ethane                                                                        1.5/--                                                                              2.4/--                                                                             4.0/0.6                                                                            7.1/--                                               Ethanol  --    1.8  --   --                                              C.sub.3                                                                            Propene/Propane                                                                        --/-- 0.3/2.4                                                                            1.1/2.2                                                                            --/4.1                                               Propanol --    --   --   --                                              C.sub.4                                                                            Butene/Butane                                                                          --/2.9                                                                              2.0/8.8                                                                            --/11.7                                                                            3.4/14.2                                             Butanol  --    --   --   --                                              C.sub.5.sup.+                                                                      Paraffins                                                                              91.0  57.9 67.2 46.9                                                 Olefins        41.4 54.7 50.7                                                 Alcohols       16.4 31.0 31.2                                                 Aldehydes      24.6 5.5  10.6                                                          C.sup.30                                                                            11.9 3.2  6.7                                                           Paraffins                                                            Paraffins      57.5 64.0 64.6                                                 Olefins        14.2 25.7 25.1                                                 Alcohols       19.8 4.4  5.8                                                  Aldehydes      6.9  2.2  3.1                                             __________________________________________________________________________     *Davidson 98025 Aluminasilicate which has similar Al/Si ratio as Y            zeolite.                                                                 

We claim:
 1. A catalyst composition prepared by a process whichcomprises:a. ion-exchanging the sodium ions of the sodium form of afaujasite type zeolite with ruthenium ions by contacting said zeolitewith a solution containing a soluble ruthenium compound. b. calciningthe ruthenium exchanged zeolite in nitrogen at a temperature rangingfrom about 300° C. to about 600° C. c. contacting theruthenium-containing zeolite with hydrogen at a temperature ranging fromabout 300° C. to about 600° C. whereby the ruthenium is reduced to themetal, d. contacting the ruthenium metal-containing zeolite with asolution of borane. e. calcining the borane treated zeolite in air at atemperature ranging from about 300° C. to about 400° C. and then f.contacting the borane-treated zeolite with hydrogen at a temperatureranging from about 300° C. to about 400° C.
 2. The composition of claim1 where in the process an aqueous solution of Ru(NH₃)₆ Cl₃ is used instep a and a tetrahydrofuran solution of borane is used in step d.